Abstract

Thus far, harmonic generation and parametric mixing of high power, ultraviolet laser radiation has provided the only means of generating coherent radiation in the wavelength region below 100 nm. Several types of ultraviolet laser sources have been upconverted to this wavelength region including Nd lasers,^1,2 dye lasers,³ and excimer lasers,³⁻⁵ using nonlinearities as high as the seventh harmonic.¹ One of the most important technical problems which must be faced in these experiments is the lack of a suitable transparent window material. Furthermore, most of the experiments necessitated the use of a nonlinear medium which itself exhibited appreciable absorption of the generated radiation. These problems have usually been overcome by employing differential pumping through restricted slits.¹,²,⁴ Recently, a special transverse flow geometry has been demonstrated⁵ which greatly improves the performance in a differential pumping system.

© 1983 Optical Society of America